Bài giảng Lập trình JAVA CSDL - Bài 3: Components - Nguyễn Hữu Thể (Phần 1)

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LẬP TRÌNH JAVA CSDL 
BÀI 3 
COMPONENTS 
Nguyễn Hữu Thể 
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Nội dung 
 JLabel 
 JButton 
 JTextField 
 JCheckBox 
 JRadioButton 
 JPanel 
 JComboBox, JList 
 JTable 
 JMenu 
 JToolBar 
 JOptionPane 
 JFileChooser 
GUI Components 
 JButton, JLabel, JTextField, JCheckBox, JRadioButton, and 
JComboBox. 
 Each GUI component class provides several constructors that 
you can use to create GUI component objects. 
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GUI Components 
// Create a button with text OK 
JButton btOK = new JButton("OK"); 
 // Create a label with text "Enter your name: " 
JLabel lbName = new JLabel("Enter your name: "); 
// Create a text field with text "Type Name Here" 
JTextField txtName = new JTextField("Type Name Here"); 
// Create a check box with text bold 
JCheckBox chkBold = new JCheckBox("Bold"); 
// Create a radio button with text red 
JRadioButton rbRed = new JRadioButton("Red"); 
// Create a combo box with choices red, green, blue 
JComboBox cboColor = new JComboBox(new String[]{"Red", 
"Green", "Blue"}); 
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Working with Components 
 javax.swing.Jcomponent 
 Several methods: 
 setEnabled(boolean): receive user input (an argument of 
true) or is inactive and cannot receive input (false). 
Components are enabled by default. 
 isEnabled() returns a boolean value. 
 setVisible(boolean): for all components. Use true to display 
a component and false to hide it. 
 isVisible() 
 setSize(int, int): width and height specified as arguments 
 setSize(Dimension) uses a Dimension 
 getSize(): returns a Dimension object with height and width 
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Working with Components 
 setText() 
 getText() 
 setValue() and getValue() for components that store a 
numeric value. 
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JLabel 
 Display Text, not editable 
 Constructor: 
 Label() : An empty label 
 JLabel(String) : A label with the specified text 
 JLabel(String, int) : A label with the specified text and 
alignment LEFT, CENTER, and RIGHT. 
 JLabel(String, Icon, int) : A label with the specified 
text, icon, and Alignment 
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JLabel 
Common Methods: 
 void setFont (Font f) 
 void setText(String S) 
 String getText() 
 void setIcon(Icon) 
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JLabel 
 Example: 
JLabel lbl=new JLabel("Họ và tên:"); 
JLabel lbl=new JLabel("Ngày sinh:"); 
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JLabel 
 The use of HTML is supported by most Swing components. 
 Example: use HTML markup to create multiline and multifont 
labels: 
JLabel lbHoten = new JLabel("Dòng 1<p 
style=\"color:red;font-size:20\">Dòng 
2"); 
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JTextField 
 Display data, Input data 
Constructors 
 JTextField(): An empty text field 
 JTextField(int): A text field with the specified width 
 JTextField(String): A text field with text 
 JTextField(String, int): A text field with the specified text 
and width 
Common Methods 
 void setText(String S) 
 String getText() 
 void setEditable(boolean b) 
 boolean isEditable() 
JTextField 
Example 
setLayout(new FlowLayout()); 
JLabel lbHoten = new JLabel("Nhập họ và tên"); 
add(lbHoten); 
JTextField txtHoten = new JTextField(20); 
add(txtHoten); 
JTextField 
 Don’t allow input data 
 txtHoten.setEditable(false) 
 To set Text in code behind for JTextField 
 txtHoten.setText("Hello world"); 
 To get Text from JTextField 
 String s = txtHoten.getText(); 
 We could convert data 
 int n = Integer.parseInt(s); //s is String 
 double d = Double.parseDouble(s); 
 float f = Float.parseFloat(s); 
 To set focus: 
 txtHoten.requestFocus(); 
JPasswordField 
 Hide the characters a user is typing into the field. 
 JPasswordField class, a subclass of JTextField. 
 JPasswordField constructor methods take the same arguments as 
those of its parent class. 
 Methods: 
 JPasswordField(String text, int columns) 
 char[] getPassword(): returns the text contained in this 
password field 
JPasswordField 
 setEchoChar(char): replacing each input character with the 
specified character 
JPasswordField pass = new JPasswordField(20); 
pass.setEchoChar('#'); 
JTextArea 
 Input is more than one line long 
Constructors 
 JTextArea(): Create a default text area. 
 JTextArea(int rows, int columns): Create a text area 
with the specified number of rows and columns. 
 JTextArea(String text) 
 JTextArea(String text, int rows, int columns) 
 JTextArea(Document doc): Create a text area that uses the 
specified Document. 
 JTextArea(Document doc, String text, int rows, int 
columns) 
JTextArea 
Common methods 
 void append(String str) 
 Append the given text to the end of the document. 
 void insert(String str, int pos) 
 Insert the specified text at the given position . To insert text 
at the beginning of the document, use a position of 0. 
 void replaceRange(String str, int start, int 
end) 
 Replace a section of the document 
JTextArea 
 public int getLineStartOffset(int line) 
throws BadLocationException 
 Return the character offset (from the beginning) that marks 
the beginning of the specified line number. 
 public int getLineEndOffset(int line) throws 
BadLocationException 
 Return the character offset (from the beginning) that marks 
the end of the specified line number. This is actually the 
offset of the first character of the next line. 
 public int getLineOfOffset(int offset) throws 
BadLocationException 
 Return the line number that contains the given character 
offset (from the beginning of the document). 
JTextArea 
JPanel contentPane = new JPanel(); 
JLabel lblNewLabel = new JLabel("Nhập dữ liệu:"); 
contentPane.add(lblNewLabel); 
JTextArea textArea = new JTextArea(3,15); 
textArea.setWrapStyleWord(true); 
textArea.setLineWrap(true); 
JScrollPane scrollPane = new JScrollPane(textArea); 
contentPane.add(scrollPane); 
JTextArea 
class MyJTextArea extends JFrame { 
private JPanel contentPane; 
public MyJTextArea() { 
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
setBounds(100, 100, 257, 128); 
contentPane = new JPanel(); 
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); 
setContentPane(contentPane); 
contentPane.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5)); 
JLabel lblNewLabel = new JLabel("Nhập dữ liệu:"); 
contentPane.add(lblNewLabel); 
JScrollPane scrollPane = new JScrollPane(); 
JTextArea textArea = new JTextArea(3,15); 
textArea.setWrapStyleWord(true); 
textArea.setLineWrap(true); 
scrollPane.setViewportView(textArea); 
contentPane.add(scrollPane); 
} 
} 
JButton 
JButton() 
Creates a button with no set text or icon. 
JButton(Action a) 
Creates a button where properties are taken from the Action 
supplied. 
JButton(Icon icon) 
Creates a button with an icon. 
JButton(String text) 
Creates a button with text. 
JButton(String text, Icon icon) 
Creates a button with initial text and an icon. 
JButton 
AccessibleContext getAccessibleContext() 
Gets the AccessibleContext associated with this 
JButton. 
String getUIClassID() 
Returns a string that specifies the name of the L&F 
class that renders this component. 
boolean isDefaultButton() 
Gets the value of the defaultButton property, which if 
true means that this button is the current default 
button for its JRootPane. 
boolean isDefaultCapable() 
Gets the value of the defaultCapable property. 
protected String paramString() 
Returns a string representation of this JButton. 
JButton 
void removeNotify() 
Overrides JComponent.removeNotify to check if this button is 
currently set as the default button on the RootPane, and if so, 
sets the RootPane's default button to null to ensure the 
RootPane doesn't hold onto an invalid button reference. 
void setDefaultCapable(boolean defaultCapable) 
Sets the defaultCapable property, which determines whether 
this button can be made the default button for its root pane. 
void updateUI() 
Resets the UI property to a value from the current look and feel. 
JButton 
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It is very important, attach event to do something that you want. 
JButton bt=new JButton("Watch"); 
bt.setIcon(new ImageIcon("mywatch.png")); 
bt.addActionListener(new ActionListener() { 
 public void actionPerformed(ActionEvent arg0) 
 { 
 //do something here coding here 
 } 
}); Add event for this button 
bt.setMnemonic('W'); Alt+W to call bt command 
JButton 
JRadioButton 
JRadioButton() Creates an initially unselected radio button with 
no set text. 
JRadioButton(Action a) Creates a radiobutton where properties 
are taken from the Action supplied. 
JRadioButton(Icon icon) Creates an initially unselected radio 
button with the specified image but no text. 
JRadioButton(Icon icon, boolean selected) Creates a radio button 
with the specified image and selection state, but no text. 
JRadioButton(String text) Creates an unselected radio button 
with the specified text. 
JRadioButton(String text, boolean selected) 
JRadioButton(String text, Icon icon) Creates a radio button that 
has the specified text and image, and that is initially unselected. 
JRadioButton(String text, Icon icon, boolean selected) 
JRadioButton - Methods 
Modifier and Type Method and Description 
AccessibleContext getAccessibleContext()Gets the 
AccessibleContext associated with this 
JRadioButton. 
String getUIClassID()Returns the name of the L&F 
class that renders this component. 
protected String paramString()Returns a string 
representation of this JRadioButton. 
void updateUI()Resets the UI property to a value 
from the current look and feel. 
JRadioButton 
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Make single choice 
Must add JRadioButton into the ButtonGroup 
if(radio.isSelected()) 
{ 
} 
JRadioButton 
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ButtonGroup & JRadioButton 
JPanel panelGroup=new JPanel(); 
panelGroup.setLayout(new BoxLayout(panelGroup, BoxLayout.Y_AXIS)); 
TitledBorder titlebor=new TitledBorder("Ý kiến của bạn:"); 
panelGroup.setBorder(titlebor); 
JRadioButton rad1=new JRadioButton("Lập trình Java rất dễ"); 
JRadioButton rad2=new JRadioButton("Design GUI Java rất dễ"); 
JRadioButton rad3=new JRadioButton("Viết web trên Java rất dễ"); 
JRadioButton rad4=new JRadioButton("Tất cả đều khó"); 
ButtonGroup group=new ButtonGroup(); 
group.add(rad1);group.add(rad2); 
group.add(rad3);group.add(rad4); 
panelGroup.add(rad1);panelGroup.add(rad2); 
panelGroup.add(rad3);panelGroup.add(rad4); 
add(panelGroup); 
JRadioButton & ButtonGroup 
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Create Border with title: 
Border bor=BorderFactory.createLineBorder(Color.RED); 
TitledBorder titlebor=new TitledBorder(bor,"Ý kiến của bạn:"); 
panelGroup.setBorder(titlebor); 
Define a buttongroup to add all radio: 
ButtonGroup group=new ButtonGroup(); 
group.add(rad1); 
And add all Radio into the pnGroup: 
panelGroup.add(rad1); 
Add panelGroup into the Window: 
add(panelGroup); 
Checkbox 
JCheckBox() Creates an initially unselected check box button with no 
text, no icon. 
JCheckBox(Action a) Creates a check box where properties are taken 
from the Action supplied. 
JCheckBox(Icon icon) Creates an initially unselected check box with 
an icon. 
JCheckBox(Icon icon, boolean selected) Creates a check box with an 
icon and specifies whether or not it is initially selected. 
JCheckBox(String text) Creates an initially unselected check box with 
text. 
JCheckBox(String text, boolean selected) 
JCheckBox(String text, Icon icon) 
JCheckBox(String text, Icon icon, boolean selected) 
Checkbox 
Make multi choice 
Set grid layout 2 rows and 2 column 
pnCheck.setLayout(new GridLayout(2, 2)); 
Create JCheckBox: 
JCheckBox chk1=new JCheckBox("Java"); 
Add chk1 into the pnCheck: 
pnCheck.add(chk1); 
Add pnCheck into the Window: 
add(pnCheck); 
BorderFactory.createEtchedBorder(Color.BLUE, Color.RED); 
Create border with 2 color: Blue, Red: 
if(chk1.isSelected()) 
{ 
 //do something 
} 
Checkbox 
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
setBounds(100, 100, 200, 150); 
panelCheck=new JPanel(); 
panelCheck.setLayout(new GridLayout(2, 2)); 
Border bor2=BorderFactory.createEtchedBorder(Color.BLUE, 
Color.RED); 
TitledBorder titlebor2=new TitledBorder(bor2, "Môn học yêu 
thích:"); 
panelCheck.setBorder(titlebor2); 
JCheckBox chk1=new JCheckBox("C/C++"); 
JCheckBox chk2=new JCheckBox("C#"); 
JCheckBox chk3=new JCheckBox("PHP"); 
JCheckBox chk4=new JCheckBox("Java"); 
panelCheck.add(chk1);panelCheck.add(chk2); 
panelCheck.add(chk3);panelCheck.add(chk4); 
add(panelCheck); 
JComboBox 
JComboBox() Creates a JComboBox with a default data model. 
JComboBox(ComboBoxModel aModel) Creates a JComboBox 
that takes its items from an existing ComboBoxModel. 
JComboBox(E[] items) Creates a JComboBox that contains the 
elements in the specified array. 
JComboBox(Vector items) Creates a JComboBox that contains 
the elements in the specified Vector. 
JComboBox 
JComboBox cbo=new JComboBox(); 
cbo.addItem("Xuất sắc"); 
cbo.addItem("Giỏi"); 
cbo.addItem("Khá"); 
cbo.addItem("Trung bình"); 
add(cbo); 
String arr[]={"Xuất sắc" ,"Giỏi" ,"Khá","Trung bình"}; 
JComboBox cbo=new JComboBox(arr); 
add(cbo); 
JComboBox 
int n=cbo.getSelectedIndex(); 
n is position that we selected 
Object o=cbo.getSelectedItem(); 
We could cast object to valid another type 
cbo.setSelectedIndex(-1); 
To clear selection